For a number of years lipolytic enzymes have been used as detergent enzymes, i.e., to remove lipid or fatty stains from clothes and other textiles.
For instance, various microbial lipases have been suggested as detergent enzymes. Examples of such lipases include a Humicola lanuginosa lipase, e.g., described in EP 258 068 and EP 305 216, a Rhizomucor miehei lipase, e.g., as described in EP 238 023, a Candida lipase, such as a C. antarctica lipase, e.g., the C. antarctica lipase A or B described in EP 214 761, a Pseudomonas lipase such as a P. alcaligenes and P. pseudoalcaligenes lipase, e.g., as described in EP 218 272, a P. cepacia lipase, e.g., as described in EP 331 376, a Bacillus lipase, e.g., a B. subtilis lipase (Dartois et al., 1993), a B. stearothermophilus lipase (JP 64/744992) and a B. pumilus lipase (EP 91 00664).
Furthermore, a number of cloned lipases have been described, including the Penicillium camembertii lipase described by Yamaguchi, S. et al., 1991, the Geotricum candidum lipase (Schimada, Y. et al., 1989), and various Rhizopus lipases such as a R. delemar lipase (Hass, M. J et al., 1991), a R. niveus lipase (Kugimiya, W. 1992), and a R. oryzae lipase.
Other types of lipolytic enzymes having been suggested as detergent enzymes include cutinases, e.g., derived from Pseudomonas mendocina as described in WO 88/09367, or a cutinase derived from Fusarium solani pisi (e.g., described in WO 90/09446).
In recent years attempts have been made to prepare lipase variants having improved properties for detergent purposes. For instance, WO 92/05249 discloses lipase variants with improved properties, in which certain characteristics of wild-type lipase enzymes have been changed by specific, i.e., site-directed modifications of their amino acid sequences. More specifically, lipase variants are described, in which one or more amino acid residues of the so-called lipid contact zone of the parent lipase has been modified.
PCT/DK93/00225 describes lipase variants with improved properties, in which an amino acid residue occupying a critical position of the lipase has been modified.
EP 407 225 discloses lipase variants with improved resistance towards proteolytic enzymes, which have been prepared by specifically defined amino acid modifications.
EP 260 105 describe hydrolases in which an amino acid residue within 15 .ANG. from the active site has been substituted.
All of the above mentioned lipase variants have been constructed by use of site-directed mutagenesis resulting in a modification of specific amino acid residues which have been chosen either on the basis of their type or on the basis of their location in the secondary or tertiary structure of the parent lipase.
An alternative approach for constructing mutants or variants of a given protein has been based on random mutagenesis. For instance, U.S. Pat. No. 4,898,331 and WO 93/01285 disclose such techniques.
A need exists for novel lipolytic enzymes having improved washing and/or dishwashing properties, and the object of the present invention is to prepare such enzymes.